The present disclosure relates to a painting robot for painting motor vehicle bodies according to the preamble of claim 1. Here, “painting robots” are to be understood to mean any program-controlled multi-axis coating machines or other movement machines. The present disclosure also relates to a corresponding operating method for such a painting robot.
In modern painting installations for painting motor vehicle bodies, use is made of multi-axis painting robots which guide as an application device for example a rotary atomizer and allow a highly efficient painting operation.
Color changes are sometimes or often necessary if the motor vehicle bodies are to be painted with differently colored paints. The known painting robots therefore have a color changer described, for example in DE 103 35 358 A1. Known painting robots may have a color changer that is connected on the inlet side to a plurality of color feed lines, via which differently colored paints are supplied. In the color changer, the individual color feed lines may open via a respective color valve into a common central color channel which, via a paint pressure regulator and a metering pump, supplies the rotary atomizer with the paint to be applied.
In this design of the color changer, the central color channel between the color changer and the main needle valve of the atomizer must generally be flushed in the event of a color change before a different paint having a new color can be applied. The flushing of the central color channel in the event of a color change is important since the paint residues remaining in the central color channel in the event of a color change would otherwise contaminate the new paint.
However, one problem here is the fact that, in the event of a color change, the volume of paint between the color changer and the main needle valve of the atomizer must be discarded so that, in the case of a color changer having 24 possible colors for example, a paint loss of between 45 and 55 ml occurs. In order to minimize the paint losses occurring during a color change, therefore, the color changer is typically mounted as close as possible to the atomizer, that is to say in the distal robot arm, which is also known as “arm 2”, and to which a wrist (hand axis) for the atomizer is attached.
However, the mounting of the color changer in the distal robot arm has until now required such a large amount of space in the distal robot arm that the known painting robots having a color changer mounted in the distal robot arm are suitable only for exterior painting, that is to say for the painting of outer faces of the motor vehicle bodies, since in exterior painting the size of the distal robot arm plays only a subordinate role.
By contrast, for painting the interior of motor vehicle bodies, it has to date not been possible to use any painting robots in which the color changer is mounted on the distal robot arm, since painting of the interior requires narrow, slim robot arms which can be introduced and articulated through body openings (e.g. door openings) into the interior of the motor vehicle bodies in order to be able to paint the inner faces in the interior. In the case of the known painting installations for painting motor vehicle bodies, therefore, in order to paint the interior, use is made of painting robots having a different design, in which the color changer is not mounted on the distal robot arm, the higher paint losses being accepted in order to allow a slimmer design of the distal robot arm to permit the robot to extend through a vehicle opening, or instead complex technologies such as, for example, paint containers within in the atomizer or pigging systems with piston metering means.
One disadvantage with the known painting installations, therefore, is the fact that different types of robots have to be used for interior painting on the one hand and for exterior painting on the other hand, which generally, and in any event in the case of a non-optimal design, also requires different application technology. However, the different designs of the painting robots and of the associated application technology lead to increased effort and cost in terms of construction and logistics of coating installations.
Accordingly, there is a need for a correspondingly improved painting robot.